CN114921703A - Surface hardened WC-Co-based hard alloy and preparation method thereof - Google Patents

Surface hardened WC-Co-based hard alloy and preparation method thereof Download PDF

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CN114921703A
CN114921703A CN202210619757.3A CN202210619757A CN114921703A CN 114921703 A CN114921703 A CN 114921703A CN 202210619757 A CN202210619757 A CN 202210619757A CN 114921703 A CN114921703 A CN 114921703A
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powder
temperature
sintering
hard alloy
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CN114921703B (en
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张钱伟
时凯华
顾金宝
廖宇
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ZIGONG CEMENTED CARBIDE CORP Ltd
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ZIGONG CEMENTED CARBIDE CORP Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
    • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
    • C22C29/08—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on tungsten carbide
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    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1003—Use of special medium during sintering, e.g. sintering aid
    • B22F3/1007—Atmosphere
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1017—Multiple heating or additional steps
    • B22F3/1021—Removal of binder or filler
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/1039—Sintering only by reaction
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/05—Mixtures of metal powder with non-metallic powder
    • C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/05—Mixtures of metal powder with non-metallic powder
    • C22C1/058—Mixtures of metal powder with non-metallic powder by reaction sintering (i.e. gasless reaction starting from a mixture of solid metal compounds)
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
    • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
    • C22C29/067—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds comprising a particular metallic binder
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Abstract

The invention discloses a WC-Co-based hard alloy with hardened surface layer and a preparation method thereof, wherein WC powder, superfine W powder and Co powder are used as raw materials, TaC is used as an inhibitor, and the WC-Co-based hard alloy with hardened surface layer is prepared by sequentially carrying out wet ball milling, screening, drying, granulating, molding and low-pressure sintering.

Description

Surface hardened WC-Co-based hard alloy and preparation method thereof
Technical Field
The invention belongs to the field of hard alloy wear-resistant materials, and particularly relates to a WC-Co-based hard alloy with a hardened surface layer and a preparation method thereof.
Background
The WC-Co hard alloy has the characteristics of high strength, high hardness and the like, is made into various tools and is widely applied to the fields of machining, mining, pavement milling, mold machining and the like. In particular, in the aspect of mechanical processing, in order to ensure the processing precision, the numerical control cutter or the welding cutter only uses the cutter body surface layer made of WC-Co hard alloy, so that the service life of the whole pair of cutters can be prolonged by enhancing the wear resistance of the WC-Co hard alloy cutter body surface layer.
At present, the method for enhancing the wear resistance of the surface layer of a cutter body aiming at a numerical control cutter and the like mainly adjusts and controls Ti gradient or surface coating and the like of the alloy surface layer by controlling sintering atmosphere. However, the process is complicated and costly, and the cost of the coating is often higher than the cost of the tool body. Thus, it has been thought by the scholars to harden the surface layer of the cemented carbide body by other means to enhance the wear resistance of the tool. For example, in the patent of Yangtian, a surface decarburized phase gradient hard material and a method for producing the same, CN113046612A,2021, the surface hardened alloy produced by the method has a surface hardened layer of less than 15 μm, and the thickness is not practical. Since the cutter body is produced and then subjected to finish machining and cutting edge treatment, i.e., grinding, passivation, etc. of the surface of the cutter body alloy, the machining allowance of the hardened layer of less than 15 μm is insufficient, and the hardened layer may be directly lost after machining. To ensure the practicability, the thickness of the hardening layer should be not less than 30 μm.
Disclosure of Invention
Aiming at the problems of short service life, high cost, low working efficiency and the like of wear-resistant tools such as a WC-Co-based alloy numerical control cutter and the like in the prior art, the invention aims to provide a WC-Co-based hard alloy with a hardened surface layer and a preparation method thereof 2 O 3 ) The mixed powder is used as a landfill material for landfill burning, the WC-Co-based hard alloy with the decarbonization phase layer thickness of 200 mu m is prepared, the service life of the WC-Co-based alloy wear-resistant tool/part can be prolonged, the replacement frequency is reduced, the production cost is reduced, and high-quality and high-efficiency production is realized.
In order to achieve the aim, the invention provides a preparation method of a WC-Co-based hard alloy with a hardened surface layer, which specifically comprises the following steps:
(1) proportioning and granulating
According to the weight parts, 92.1-92.55 parts of WC powder, 0.95-2.4 parts of superfine W powder and 5.5-6.5 parts of Co powder are taken as raw materials, the sum of the proportions of the three components is 100 parts, TaC is taken as an inhibitor, and the addition amount of the TaC is 0.1-0.3% of the total mass of the WC powder, the superfine W powder and the Co powder;
weighing the materials according to the proportion, and then sequentially adding a forming agent, performing wet ball milling, screening, drying and granulating on the weighed materials to form a granular mixture;
(2) shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing into a hard alloy blank;
(3) sintering
Putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 50-90 wt% of corundum powder and 10-50 wt% of W powder, and sintering in four stages:
the first stage is as follows: removing the forming agent at 250-460 ℃;
and a second stage: heating to 1220-1240 ℃, preserving heat for 0.9-1.1 h, introducing argon into the low-pressure sintering furnace at the temperature until the vacuum degree in the furnace is 2.5-3.5 kPa after the heat preservation time is over, then heating to 1450-1470 ℃, preserving heat for 0.9-1.1 h, and completing vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature until the pressure in the furnace is 4-6 MPa, and preserving the heat in an argon atmosphere for 1.2-1.5 hours to finish the low-pressure sintering;
a fourth stage: cooling to room temperature along with the furnace to obtain the WC-Co-based hard alloy with hardened surface layer.
In the preparation method of the WC-Co-based hard alloy with the hardened surface layer, the material is prepared by combining a powder metallurgy method and low-pressure sintering, and because a certain amount of superfine W powder is added into the raw material, the carbon content of the whole WC-Co alloy is in the boundary water of a precipitated phase of a decarburized phaseFlat and sintered using W powder and corundum powder (Al) 2 O 3 ) The mixed powder is used as a landfill material for landfill burning. Because the whole carbon content of the alloy is in the phase boundary position where the decarbonized phase is separated out, the powder mixed by the corundum powder and the W powder is coated outside the alloy surface layer, the corundum powder has the carbon-attracting effect, the carbon on the alloy surface layer can be captured, so that a low-carbon environment is manufactured for the alloy surface layer, and meanwhile, the W powder provides required raw materials for forming the decarbonized phase, so that the W, Co and WC on the surface layer can be combined with each other very easily to form the decarbonized phase (Co, Co and WC) x W y C z ) But not in the core because the core does not deprive the carbon environment. The decarbonized phase has the characteristics of high hardness and high wear resistance, so that the decarbonized phase with high concentration is precipitated on the surface layer, and the hardness and the wear resistance of the alloy surface layer are enhanced. In addition, in combination with the four-stage specific sintering process, the decarburized phase exists in a dispersed and distributed granular form, but does not branch and only exists on the surface layer of the alloy, and the thickness of the precipitated decarburized phase layer can reach 200 mu m. Therefore, the WC-Co-based alloy prepared by the method can show excellent wear resistance on the surface layer of the alloy on the premise of not remarkably reducing the strength. The technology can be applied to all WC-xCo (x is 3% -20%) alloys to improve the surface wear resistance of the WC-xCo alloys.
In the preparation method of the WC-Co-based hard alloy with hardened surface layer, the hard alloy is composed of insoluble carbide with high compressive strength, high hardness and high elastic modulus, and the powder of the hard alloy is difficult to generate plastic deformation in the pressing process. In order to improve the powder forming performance, increase the briquetting strength and facilitate the transfer of the pressed compact, a forming agent is added into the powder material before forming. The forming agent can be one of but not limited to rubber, paraffin, polyethylene glycol or SD glue, and the addition amount is 1-3% of the total weight of the raw materials. In the invention, paraffin is preferably used as a forming agent, and the addition amount is preferably 1-3% of the total weight of the three raw materials (raw material WC powder, superfine W powder and Co powder).
In the preparation method of the WC-Co-based hard alloy with hardened surface layer, the wet ball milling has the effect of uniformly mixing all materials (WC powder, superfine W powder, Co powder and TaC), a wet milling medium is required to be added during the wet ball milling, the hard alloy ball milling process mainly adopts two types of liquid, namely alcohol and normal hexane as the wet milling medium at present, when the alcohol is used as the wet milling medium, the wettability of the alcohol and the raw materials such as WC, Co and the like is good, so the grinding efficiency is high, a cosolvent (also called surfactant) is not required to be added, when the hexane is used as the wet milling medium, the wettability of the raw materials such as hexane, WC, Co and the like is not good, the grinding efficiency is low, the problems that slurry is easy to adhere to the wall and the alloy magnetic force is low exist in the ball milling process, a trace amount of cosolvent is required to be added for increasing the wettability of the raw materials such as WC and the like by the hexane, the hexane and the cosolvent are preferably adopted as the wet milling medium, and are added during the wet ball milling process, volume of hexane (ml): the total mass (g) of the three raw materials is 3-5: 1, the ball material ratio is 3-2: 1, ball milling time is 13-15 h, and ball milling rotating speed is 45-55 r/min. The cosolvent can be selected from but not limited to oleic acid, esoxim or stearic acid, the oleic acid and the esoxim are liquid, and the addition of the oleic acid and the esoxim is difficult to be accurate, so that the stearic acid is preferably used as the cosolvent in the invention.
The drying after the wet ball milling is to quickly volatilize a wet milling medium contained in the mixed material, the drying temperature is generally 60-80 ℃, and the drying is carried out under normal pressure or vacuum. It should be noted that, in addition to the forming agent being added before wet grinding, the forming agent may be added after drying after wet grinding, and the drying, screening, granulating and forming may be sequentially performed after the forming agent is added. The addition sequence of the forming agent has no influence on the performance of the invention, and can be adjusted by the person skilled in the art according to specific production conditions. Further, the screening is performed by using a 300-800 mesh screen in order to obtain powder meeting the granulation requirements. The forming die is designed and manufactured according to the shape and the size of the prepared hard alloy product.
In the above method for preparing a surface hardened WC — Co based cemented carbide, in the step (3), it is preferable to bury a cemented carbide blank with a mixed powder composed of 80 wt% of corundum powder and 20 wt% of W powder. Furthermore, the amount of the burning material to be buried is conventional, and can be adjusted by a person skilled in the art according to actual conditions.
In the preparation method of the WC-Co-based hard alloy with the hardened surface layer, in the first sintering stage, preferably, the temperature is increased from room temperature to 240-260 ℃, then the temperature is increased to 380-400 ℃, the temperature is kept for 1.5-2.5 h, then the temperature is increased to 440-460 ℃, the temperature is kept for 6-7 h, and the forming agent is removed. Furthermore, the temperature rising speed from room temperature to 240-260 ℃ is preferably 4.5-5.5 ℃/min, the temperature rising speed from 380-400 ℃ is preferably 0.7-1.7 ℃/min, and the temperature rising speed from 440-460 ℃ is preferably 1.8-2.8 ℃/min.
In the second sintering stage, the temperature rising speed of the hard WC-Co hard alloy is preferably 3.7-4.7 ℃/min when the hard WC-Co hard alloy is heated to 940-960 ℃, the temperature rising speed of the hard WC-Co hard alloy is preferably 4.2-5.2 ℃/min when the hard WC-Co hard alloy is heated to 1220-1240 ℃, and the temperature rising speed of the hard WC-Co hard alloy is preferably 3.3-4.3 ℃/min when the hard WC-Co hard alloy is heated to 1450-1470 ℃.
In the method for preparing the surface hardened WC-Co based hard alloy, in the fourth stage of sintering, preferably, the temperature is reduced to 790-810 ℃ at the cooling rate of 2.25-3.25 ℃/min, and then the temperature is reduced to room temperature at the cooling rate of 1.44-2.44 ℃/min.
In the preparation method of the surface hardened WC-Co based hard alloy, superfine W powder with the standard particle size in the field can be adopted as the superfine W powder, the particle size of the superfine W powder is preferably 24-30 mu m, the particle size of Co is preferably 0.8-1.2 mu m, and the average particle size of WC powder is preferably 24-30 mu m.
The invention also provides the WC-Co-based hard alloy with the hardened surface layer prepared by the preparation method. The thickness of the precipitated decarburized phase layer of the WC-Co-based hard alloy with the hardened surface layer prepared by the method can reach 200 mu m, the later-stage processability and excellent wear resistance of the alloy are ensured, and the decarburized phase exists in the form of dispersed particles, is not dendritic and only exists on the surface layer of the alloy.
Compared with the prior art, the surface hardened WC-Co based hard alloy and the preparation method thereof provided by the invention have the following beneficial effects:
(1) the preparation method of the WC-Co-based hard alloy with the hardened surface layer combines the specific low-pressure sintering process flow and process parameters through the powder metallurgy method, and adopts W powder and corundum powder (Al) during sintering 2 O 3 ) The mixed powder is used as landfillThe material is buried and sintered, a low-carbon environment is manufactured on the alloy surface layer through the corundum powder, meanwhile, the W powder provides a required raw material for forming a decarburized phase, so that a high-concentration decarburized phase can be precipitated on the WC-Co-based hard alloy surface layer, and the hardness and the wear resistance of the alloy surface layer are enhanced.
(2) The WC-Co-based hard alloy with the hardened surface layer prepared by the method provided by the invention has the advantages that the thickness of the decarburized phase layer can reach 200 mu m, the reliable guarantee is provided for the later-stage machinability of the alloy, the decarburized phase exists in the form of dispersed particles instead of dendritic particles and only exists on the alloy surface layer, the hardness and the wear resistance of the alloy surface layer are obviously enhanced, the service life of the alloy tool/part can be obviously prolonged after the tool/part is manufactured, the replacement frequency of a numerical control cutter/wear-resistant part is reduced, the working efficiency is improved, the production cost is reduced, and the market competitiveness is higher.
(3) The method provided by the invention can be applied to strengthening the WC-Co alloy surface of a tool such as lathe machining and the like, can also be applied to improving the surface wear resistance of all hard alloys taking Co as a binder phase in an extending way, has good application prospect, and is worth being popularized in the industry.
Drawings
FIG. 1 is a cross-sectional metallographic view of a case hardened WC — Co based cemented carbide sample prepared in example 1;
FIG. 2 is a cross-sectional metallographic view of a sample of WC-Co based cemented carbide prepared in example 2;
fig. 3 is a cross-sectional SEM image of a WC-Co based cemented carbide sample prepared in example 3.
Detailed Description
So that the technical solutions of the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings, it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, belong to the present invention.
The WC average particle size used in the following examples was 27 μm, the ultrafine W powder average particle size was 0.4 μm, and the Co powder average particle size was 1 μm, all of which were commercially available. Further, in the following examples, 1 part by weight is equal to 10 g.
Example 1
The surface hardened WC — Co based cemented carbide provided in this embodiment uses the following raw materials and process steps:
(1) proportioning and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. After the ball milling is finished, the slurry passes through a 60-mesh screen and is dried for 1h in vacuum at 75 ℃ to obtain a dry material, and the dry material is granulated by a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank under the pressing pressure of 5 MPa;
(3) sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 80% of corundum powder and 20% of W powder, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy with hardened surface layer.
Example 2
The difference between the surface-hardened WC-Co-based cemented carbide provided in this example and example 1 is that the proportions of WC powder, W powder, and Co powder are different, and the raw materials and process steps used are as follows:
(1) proportioning and granulating
Weighing 92.1 parts of tungsten carbide, 1.7 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. After the ball milling is finished, the slurry passes through a 60-mesh screen and is dried for 1h in vacuum at 75 ℃ to obtain a dry material, and the dry material is granulated by a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank under the pressing pressure of 5 MPa;
(3) sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 80% of corundum powder and 20% of W powder, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving heat for 2h, raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving heat for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy with hardened surface layer.
Example 3
The difference between the WC-Co based cemented carbide hardened by the surface layer provided in this example and examples 1 and 2 is that the proportions of WC powder, W powder, and Co powder are different, and the raw materials and process steps used are as follows:
(1) compounding and granulating
92.55 parts of tungsten carbide, 1.95 parts of superfine W powder and 5.5 parts of superfine Co powder are weighed according to the weight percentage, the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid are weighed based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. After the ball milling is finished, the slurry passes through a 60-mesh screen and is dried for 1h in vacuum at 75 ℃ to obtain a dry material, and the dry material is granulated by a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank under the pressing pressure of 5 MPa;
(3) sintering of
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 80% of corundum powder and 20% of W powder, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at a speed of 4.2 ℃/min, raising the temperature to 1230 ℃ at a speed of 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after the heat preservation is finished, and continuously raising the temperature to 1460 ℃ at a speed of 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: the temperature is reduced to 800 ℃ at the speed of 2.75 ℃/min, and then the temperature is reduced to room temperature at the speed of 1.94 ℃/min, and the WC-Co base hard alloy with hardened surface layer is obtained.
Example 4
The difference between the surface-hardened WC — Co-based cemented carbide provided in this example and example 1 is the sintering process, and the raw materials and process steps used are as follows:
(1) proportioning and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. And after the ball milling is finished, the slurry passes through a 60-mesh screen, is subjected to vacuum drying at 75 ℃ for 1h to obtain a dry material, and the dry material is granulated through a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank at a pressing pressure of 5 MPa;
(3) sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 80% of corundum powder and 20% of W powder, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 240 ℃ at the speed of 5 ℃/min, raising the temperature to 380 ℃ at the speed of 1.2 ℃/min, preserving heat for 2h, raising the temperature to 440 ℃ at the speed of 2.3 ℃/min, preserving heat for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 940 ℃ at a speed of 4.2 ℃/min, raising the temperature to 1220 ℃ at a speed of 4.7 ℃/min, preserving the heat for 1h, introducing argon into the low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to be 3kPa, and then continuing raising the temperature to 1450 ℃ at a speed of 3.8 ℃/min, preserving the heat for 1h, and completing vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1450 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: the temperature is reduced to 800 ℃ at the speed of 2.75 ℃/min, and then the temperature is reduced to room temperature at the speed of 1.94 ℃/min, and the WC-Co base hard alloy with hardened surface layer is obtained.
Example 5
The difference between the surface-hardened WC-Co-based cemented carbide provided in this example and examples 1 and 4 is the sintering process, and the raw materials and process steps used are as follows:
(1) compounding and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. And after the ball milling is finished, the slurry passes through a 60-mesh screen, is subjected to vacuum drying at 75 ℃ for 1h to obtain a dry material, and the dry material is granulated through a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank under the pressing pressure of 5 MPa;
(3) sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 80% of corundum powder and 20% of W powder, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 260 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 960 ℃ at 4.2 ℃/min, raising the temperature to 1240 ℃ at 4.7 ℃/min, preserving the heat for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1470 ℃ at 3.8 ℃/min, preserving the heat for 1h and finishing the vacuum sintering;
and a third stage: after the vacuum heat preservation is finished, closing the vacuum, introducing argon into the low-pressure sintering furnace at the temperature of 1470 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving the heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy with hardened surface layer.
Example 6
The difference between the WC — Co-based cemented carbide hardened by the surface layer provided in this example and example 1 is the TaC content, and the raw materials and process steps used are as follows:
(1) proportioning and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.3 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. After the ball milling is finished, the slurry passes through a 60-mesh screen and is dried for 1h in vacuum at 75 ℃ to obtain a dry material, and the dry material is granulated by a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank at a pressing pressure of 5 MPa;
(3) sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 80% of corundum powder and 20% of W powder, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy with hardened surface layer.
Examples 7 to 10
The surface-hardened WC — Co-based cemented carbide provided in this example is different from example 1 in the ratio of corundum powder to W powder, and the specific amount is shown in table 1:
TABLE 1
Examples Corundum powder (%) W powder (%)
Example 1 80 20
Example 7 50 50
Example 8 60 40
Example 9 70 30
Example 10 90 10
Comparative example 1
The comparative example provides a WC-Co based cemented carbide, which, compared to example 1, differs in that no sintering material is used to fill the cemented carbide blank, and the raw materials and process steps used are as follows:
(1) proportioning and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. After the ball milling is finished, the slurry passes through a 60-mesh screen and is dried for 1h in vacuum at 75 ℃ to obtain a dry material, and the dry material is granulated by a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank under the pressing pressure of 5 MPa;
(3) sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy.
Comparative example 2
Comparison of booksExample a WC-Co based cemented carbide was provided which compared to example 1 was distinguished by the use of 100% corundum powder (Al) 2 O 3 ) The burying material is used for burying the hard alloy blank, and the used raw materials and the process steps are as follows:
(1) compounding and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. After the ball milling is finished, the slurry passes through a 60-mesh screen and is dried for 1h in vacuum at 75 ℃ to obtain a dry material, and the dry material is granulated by a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank under the pressing pressure of 5 MPa;
(3) sintering
Putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, and adopting 100% of corundum powder (Al) 2 O 3 ) The hard alloy blank is buried and sintered in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving heat for 2h, raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving heat for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy.
Comparative example 3
This comparative example provides a WC-Co based cemented carbide that differs from comparative example 2 in that two sinterings are used, followed by 100% corundum powder (Al) after the first sintering is completed 2 O 3 ) The burying sintering material is used for burying the primary sintering green body, and the used raw materials and the process steps are as follows:
(1) proportioning and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and the materials are subjected to ball milling by a roller ball mill at the rotating speed of 500r/min for 14 h. After the ball milling is finished, the slurry passes through a 60-mesh screen and is dried for 1h in vacuum at 75 ℃ to obtain a dry material, and the dry material is granulated by a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank at a pressing pressure of 5 MPa;
(3) primary sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving heat for 2h, raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving heat for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: the temperature is reduced to 800 ℃ at the speed of 2.75 ℃/min, and then the temperature is reduced to room temperature at the speed of 1.94 ℃/min, and a primary sintering green body is obtained.
(4) Secondary sintering
Adopting 100 percent corundum powder (Al) to the primary sintered blank prepared in the step (3) 2 O 3 ) The hard alloy blank is buried and sintered in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy.
Comparative example 4
Compared with the comparative example 3, the difference of the WC-Co-based hard alloy is that after the primary sintering is finished, a primary sintered blank is buried by adopting a buried sintering material consisting of mixed powder of 80% of corundum powder and 20% of W powder, and the used raw materials and the process steps are as follows:
(1) compounding and granulating
Weighing 92.4 parts of tungsten carbide, 1.4 parts of superfine W powder and 6.2 parts of superfine Co powder according to the weight percentage, wherein the total weight of the tungsten carbide, the superfine W powder and the superfine Co powder is 1Kg, and weighing 0.2 wt% of TaC, 2 wt% of paraffin and 0.04% of stearic acid based on the total weight of the WC powder, the superfine W powder and the Co powder.
And (2) adding the weighed materials into a ball milling tank together, wherein a milling body is an alloy rod, the ball-material ratio is 2:1, a milling medium is hexane, the addition amount of the hexane is 400mL, and ball milling is carried out by adopting a roller ball mill at the rotating speed of 500r/min for 14 h. And after the ball milling is finished, the slurry passes through a 60-mesh screen, is subjected to vacuum drying at 75 ℃ for 1h to obtain a dry material, and the dry material is granulated through a granulator to form a granular mixture.
(2) Shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing the granular mixture into a hard alloy blank under the pressing pressure of 5 MPa;
(3) primary sintering
And (3) putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, and sintering in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at a speed of 4.2 ℃/min, raising the temperature to 1230 ℃ at a speed of 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after the heat preservation is finished, and continuously raising the temperature to 1460 ℃ at a speed of 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: the temperature is reduced to 800 ℃ at the speed of 2.75 ℃/min, and then the temperature is reduced to room temperature at the speed of 1.94 ℃/min, and a primary sintering green body is obtained.
(4) Secondary sintering
Adopting 100 percent corundum powder (Al) to the primary sintered blank prepared in the step (3) 2 O 3 ) The hard alloy blank is buried and sintered in four stages:
the first stage is as follows: raising the temperature from room temperature to 250 ℃ at the speed of 5 ℃/min, then raising the temperature to 390 ℃ at the speed of 1.2 ℃/min, preserving the temperature for 2h, and then raising the temperature to 450 ℃ at the speed of 2.3 ℃/min, preserving the temperature for 6.5h, and finishing dewaxing;
and a second stage: raising the temperature to 950 ℃ at 4.2 ℃/min, raising the temperature to 1230 ℃ at 4.7 ℃/min, preserving the temperature for 1h, introducing argon into a low-pressure sintering furnace at the temperature to adjust the vacuum degree in the furnace to 3kPa after finishing the heat preservation, and then continuously raising the temperature to 1460 ℃ at 3.8 ℃/min, preserving the temperature for 1h and finishing the vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature of 1460 ℃ until the pressure in the furnace reaches 5MP, and continuously preserving heat and sintering for 80min in the argon atmosphere to finish the low-pressure sintering;
a fourth stage: firstly reducing the temperature to 800 ℃ at the speed of 2.75 ℃/min, and then reducing the temperature to room temperature at the speed of 1.94 ℃/min, thus obtaining the WC-Co based hard alloy.
The WC — Co-based cemented carbide samples prepared in example 1 and comparative examples 1 to 4 were subjected to the following property analysis.
The WC-Co based cemented carbide sample prepared in example 1 was subjected to cross-sectional polishing treatment, and then the cross-sectional morphology and physical properties were characterized. The cross-sectional morphology of the WC-Co-based cemented carbide sample is shown in fig. 1. In order to more intuitively observe whether the surface layer has a hardening phase (decarbonized phase), the decarbonized phase can be reddish brown under the observation of color metallographic phase after the surface metallographic corrosion, as can be seen from figure 1, the alloy surface layer has a large number of hardening phases (decarbonized phases), the edge thickness of the alloy surface layer is as high as 181 micrometers, the thickness has a processing allowance in the numerical control cutter, and the practicability is strong. The alloy sample was tested for density, coercivity, and hardness, and had a density of 14.98g/cm 3 The coercive force was 6.2KA/m, the core region hardness was 87.5HRA, and the surface region hardness was 91.2 HRA. The results show that the alloy surface layer is obviously hardened due to the precipitation of the decarburized phase, so that the wear resistance of the alloy surface layer is enhanced.
The WC-Co based cemented carbide sample prepared in comparative example 1 was subjected to cross-sectional polishing treatment,then the cross-sectional morphology and physical properties were characterized. The cross-sectional morphology of the WC-Co based cemented carbide sample is shown in fig. 2. As can be seen from fig. 2, no significant decarburized phase was observed in the Co phase of the WC — Co-based cemented carbide sample. The alloy samples were tested for density, coercivity, and hardness, and the density was 14.96g/cm 3 The coercive force was 5.9KA/m, and the hardness was 87.5 HRA.
The WC-Co-based cemented carbide sample prepared in comparative example 2 was subjected to cross-sectional polishing treatment, and then the cross-sectional morphology and physical properties were characterized, and the cross-sectional morphology of the WC-Co-based cemented carbide sample is shown in fig. 3. The cross-sectional morphology was observed by SEM and confirmed by EDS, and the alloy surface layer was found to have a hardened phase (decarburized phase) and a thickness of about 10 μm. The alloy samples were tested for density, coercivity, and hardness, and the density of the alloy samples was 14.96g/cm 3 The coercive force was 6.0KA/m, and the hardness was 87.6 HRA. In view of the narrow thickness of the layer containing the hardening phase, hardness test was not separately performed on the hardened layer region.
The WC-Co-based cemented carbide sample prepared in comparative example 3, in which no hardening phase (decarburized phase) was found in the surface layer, had a density of 14.96g/cm 3 The coercive force was 5.6KA/m, and the hardness was 87.4 HRA. The WC-Co based cemented carbide sample prepared in comparative example 4, in which no hardening phase (decarburized phase) was found in the surface layer, had a density of 14.96g/cm 3 The coercive force was 5.7KA/m, and the hardness was 87.4 HRA. Comparative examples 3 and 4 show that it is difficult to form a hardened phase (decarburized phase) on the surface of the alloy sample by filling the alloy sample with a filler after primary sintering, i.e., alloying.
In summary, the WC-Co-based hard alloy with the surface layer having high hardness and wear resistance and the preparation method thereof provided by the invention adopt a powder metallurgy method combined with low-pressure sintering, and adopt WC, ultrafine W powder, ultrafine Co powder and TaC as raw materials, and a biscuit sample is obtained by mixing, ball milling, drying, granulating and pressing, and finally, the WC-Co-based hard alloy with the surface layer having high hardness and wear resistance is obtained by sintering through a specific process. The WC-Co-based alloy prepared by the method has excellent wear resistance on the premise of not remarkably reducing the strength, and the method has simple process and easily obtained raw materials, thereby being convenient for industrial production and having good application prospect.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.

Claims (10)

1. A preparation method of a WC-Co-based hard alloy with a hardened surface layer is characterized by comprising the following steps: the method comprises the following steps:
(1) compounding and granulating
According to the weight portion, 92.1-92.55 portions of WC powder, 0.95-2.4 portions of superfine W powder and 5.5-6.5 portions of Co powder are taken as raw materials, the sum of the ratio of the three components is 100 portions, TaC is taken as an inhibitor, and the addition amount of the TaC is 0.1-0.3% of the total mass of the WC powder, the superfine W powder and the Co powder;
weighing the materials according to the proportion, and then sequentially adding a forming agent, performing wet ball milling, screening, drying and granulating on the weighed materials to form a granular mixture;
(2) shaping of
Filling the granular mixture formed in the step (1) into a cavity of a die, and pressing to form a hard alloy blank;
(3) sintering
Putting the hard alloy blank prepared in the step (2) into a low-pressure sintering furnace, burying the hard alloy blank by adopting mixed powder consisting of 50-90 wt% of corundum powder and 10-50 wt% of W powder, and sintering in four stages:
the first stage is as follows: removing the forming agent at 250-460 ℃;
and a second stage: heating to 1220-1240 ℃, preserving heat for 0.9-1.1 h, introducing argon into the low-pressure sintering furnace at the temperature until the vacuum degree in the furnace is 2.5-3.5 kPa after the heat preservation time is over, then heating to 1450-1470 ℃, preserving heat for 0.9-1.1 h, and completing vacuum sintering;
and a third stage: closing the vacuum after the vacuum heat preservation is finished, introducing argon into the low-pressure sintering furnace at the temperature until the pressure in the furnace is 4-6 MPa, and preserving the heat in an argon atmosphere for 1.2-1.5 hours to finish the low-pressure sintering;
a fourth stage: and cooling to room temperature along with the furnace to obtain the WC-Co based hard alloy with hardened surface layer.
2. The method of making a surface hardened WC-Co based cemented carbide according to claim 1, characterized in that: and adding hexane and a cosolvent during wet ball milling, wherein the ball-to-material ratio is 3-2: 1, the ball milling time is 13-15 hours, and the cosolvent is one of stearic acid, oleic acid or isoethamine.
3. The method of making a surface hardened WC-Co based cemented carbide according to claim 1, characterized in that: in the step (3), the hard alloy blank is buried by adopting mixed powder consisting of 80 wt% of corundum powder and 20 wt% of W powder.
4. The method of making a surface hardened WC-Co based cemented carbide according to claim 1, characterized in that: the forming agent is one of rubber, paraffin, polyethylene glycol and SD (secure digital) glue, and the addition amount of the forming agent is 1-3% of the total weight of the three raw materials.
5. The method of preparing a case hardened WC-Co based cemented carbide according to claim 1, characterized in that: in the first stage of sintering, the temperature is raised from room temperature to 240-260 ℃, then raised to 380-400 ℃, and kept for 1.5-2.5 h, and then raised to 440-460 ℃ and kept for 6-7 h to complete removal of the forming agent.
6. The method of making a surface hardened WC-Co based cemented carbide according to claim 5, characterized in that: in the first stage of sintering, the temperature is raised from room temperature to 240-260 ℃ at a heating rate of 4.5-5.5 ℃/min, then raised to 380-400 ℃ at a heating rate of 0.7-1.7 ℃/min, and then raised to 440-460 ℃ at a heating rate of 1.8-2.8 ℃/min.
7. The method of making a surface hardened WC-Co based cemented carbide according to claim 1, characterized in that: in the second stage of sintering, the temperature is raised to 940-960 ℃ at a heating rate of 3.7-4.7 ℃/min, is raised to 1220-1240 ℃ at a heating rate of 4.2-5.2 ℃/min, and is raised to 1450-1470 ℃ at a heating rate of 3.3-4.3 ℃/min.
8. The method of preparing a case hardened WC-Co based cemented carbide according to claim 1, characterized in that: in the fourth stage of sintering, the temperature is reduced to 790-810 ℃ at the cooling speed of 2.25-3.25 ℃/min, and then the temperature is reduced to room temperature at the cooling speed of 1.44-2.44 ℃/min.
9. A method of producing a surface hardened WC-Co based cemented carbide according to any one of claims 1 to 8, characterized in that: the average particle size of the WC powder is 24-30 mu m, the average particle size of the superfine W powder is 0.2-1.0 mu m, and the average particle size of the Co powder is 0.8-1.2 mu m.
10. A case hardened WC-Co based cemented carbide produced by the production method according to any one of claims 1 to 9.
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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63169356A (en) * 1987-01-05 1988-07-13 Toshiba Tungaloy Co Ltd Surface-tempered sintered alloy and its production
US6641918B1 (en) * 1999-06-03 2003-11-04 Powdermet, Inc. Method of producing fine coated tungsten carbide particles
JP2005248309A (en) * 2004-03-08 2005-09-15 Tungaloy Corp Cemented carbide and coated cemented carbide
KR20060069622A (en) * 2004-12-16 2006-06-22 재단법인 포항산업과학연구원 Method of post heat-treatment for the improvement in wear-resistance of nano-structured wc-co coatings
CN102126025A (en) * 2011-02-22 2011-07-20 中南大学 Process for preparing surface decarbonized WC-Co gradient hard alloy preform
CN104498684A (en) * 2015-01-19 2015-04-08 四川科力特硬质合金股份有限公司 Decarburization method for hard alloy in vacuum sintering furnace
CN105331868A (en) * 2015-11-10 2016-02-17 中南大学 Preparation method of WC-Co hard alloy of gradient structure
CN106987752A (en) * 2017-05-02 2017-07-28 四川大学 A kind of gradient hard alloy preparation method of case-carbonizing
CN111575567A (en) * 2020-04-09 2020-08-25 江西理工大学 Regeneration method of waste high-cobalt coarse-grain hard alloy
CN113046612A (en) * 2019-12-27 2021-06-29 四川大学 Surface layer decarburization phase gradient hard alloy material and preparation method thereof

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63169356A (en) * 1987-01-05 1988-07-13 Toshiba Tungaloy Co Ltd Surface-tempered sintered alloy and its production
US6641918B1 (en) * 1999-06-03 2003-11-04 Powdermet, Inc. Method of producing fine coated tungsten carbide particles
JP2005248309A (en) * 2004-03-08 2005-09-15 Tungaloy Corp Cemented carbide and coated cemented carbide
KR20060069622A (en) * 2004-12-16 2006-06-22 재단법인 포항산업과학연구원 Method of post heat-treatment for the improvement in wear-resistance of nano-structured wc-co coatings
CN102126025A (en) * 2011-02-22 2011-07-20 中南大学 Process for preparing surface decarbonized WC-Co gradient hard alloy preform
CN104498684A (en) * 2015-01-19 2015-04-08 四川科力特硬质合金股份有限公司 Decarburization method for hard alloy in vacuum sintering furnace
CN105331868A (en) * 2015-11-10 2016-02-17 中南大学 Preparation method of WC-Co hard alloy of gradient structure
CN106987752A (en) * 2017-05-02 2017-07-28 四川大学 A kind of gradient hard alloy preparation method of case-carbonizing
CN113046612A (en) * 2019-12-27 2021-06-29 四川大学 Surface layer decarburization phase gradient hard alloy material and preparation method thereof
CN111575567A (en) * 2020-04-09 2020-08-25 江西理工大学 Regeneration method of waste high-cobalt coarse-grain hard alloy

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